/**
  * Helper method for validation external URL
  *
  * @param WikiaValidator $validator an instance of WikiaValidator ie. WikiaUrlValidator
  *
  * @return bool
  */
 public function isValidUrl(WikiaValidator $validator)
 {
     $externalUrl = $this->getData('articleTitleOrExternalUrl');
     $valid = false;
     if (!empty($externalUrl) && $validator->isValid($externalUrl) || empty($externalUrl)) {
         $valid = true;
     }
     return $valid;
 }